This invention relates to hearing aids and more particularly to an ear mold for a hearing aid which incorporates a plurality of reflection and resonance chambers. Heretofore, hearing aids have been developed for amplifying sound waves and to conduct the amplified waves to the tympanic membrane of the ear, in order to improve the hearing of an individual. Presently manufactured hearing aid apparatus includes an amplifier, transducer and an ear mold all or parts of which are insertable into the ear.
Amplified sound wave energy created by the amplifier and transducer is usually air conducted to the ear mold, wherein the longitudinal canal or conduit conveys the amplifier sound wave energy to the tympanic membrane of the ear where the normal hearing process is commenced. That is, the sound wave energy strikes the tympanic membrane and then travels onto the malleus, the incus, the stapes, to the oval window and on through the fluid of the inner ear where the cochlea contains the organ of the corti with associated nerve endings of the auditory nerve from the brain.
A disadvantage of the presently manufactured ear molds is that improved hearing is contingent solely upon sound wave amplification. If, for example, otosclerosis has rendered immovable, or partially immovable, the steps due to ankylosis in the oval window, the effectiveness of a hearing aid is lost. Also in many instances where a high level amplification is necessary sound saturation results, whereby the normal process of hearing becomes traumatized and a degree of hearing is not aided insofar as intelligibility is concerned.
In addition to the normal air conduction process of hearing by way of the tympanic membrane, sound wave energy can also be conducted to the hearing part of the brain by means of bone conduction. In bone conduction hearing, vibratory sound wave energy is transmitted to the brain over a separate and distinct route from the normal hearing process. Sound wave energy directly enters the mastoid process and other associated bones of the head and travels by bone conduction to the hearing part of the brain for discrimination and interpretation. Thus bone conduction hearing can be beneficial in reinforcing sound wave energy transmitted to the brain by the normal air conduction process. It is therefore an object of this invention to provide an improved acoustic ear mold for bone conduction of sound wave energy in combination with conventional air born sound wave energy to the ear.
It is another object of this invention to present an improved ear mold wherein amplified sound waves are conducted to the tympanic membrane of the ear and simultaneously therewith to the bones of the mastoid process, and other bones such that sound wave energy is conveyed by two separate routes to the hearing, understanding part of the brain for speech and sound discrimination, interpretation and understanding.